In the manufacture and finishing of organic chemicals and plastics, a wide variety of hydrocarbon streams have readily occurring residual components such as low molecular weight polymeric gums. Such gums are generally oligomeric byproducts of many chemical reactions, especially polymerization reactions, and can build up in reactant recycle streams of continuous operations. Unless the buildup of such materials is effectively prevented, they will accumulate and can cause fouling of equipment, especially heat exchangers and compressors, with concomitant operational difficulties.
Polymers comprising .alpha.-olefins and maleic anhydride are well known. Rossi U.S. Pat. No. 4,240,916 discloses an oil soluble copolymer composed of about equimolar amounts of 1-olefins and maleic anhydride useful as a lubricating oil pour point depressant wherein the 1-olefins are a mixture of C.sub.1 -C.sub.14 and C.sub.20 -C.sub.28 monomers. The pour point depressant activity is said to be enhanced by esterification of the copolymer with a C.sub.1 -C.sub.4 alcohol.
Rossi U.S. Pat. No. 4,151,069 discloses olefin-dicarboxylic anhydride copolymers and their ester derivatives having C.sub.18 -C.sub.50 linear alkyl side chains. The polymers and derivatives are said to be useful in amounts of up to 5 weight percent as filtration aids in low-temperature solvent dewaxing of waxy lubricating oils containing 5-30 weight percent wax.
Similarly, Miller U.S. Pat. No. 3,694,176, discloses polymers of ethylene and ethylenically unsaturated dicarboxylic acids, anhydrides or esters as wax crystal modifiers, pour point depressants and dewaxing aids in petroleum oil.
Rossi U.S. patent application, Ser. No. 515,562, filed Oct. 17, 1974, abandoned, discloses that partial alkyl ester-partial amide derivatives of low molecular weight maleic anhydride/1-olefin copolymers are useful in mineral oil lubricants as pour point depressants, viscosity index improvers and sludge inhibitors.
Japanese Kokai 62-018,494 discloses low temperature flow improvers for fuel oils which are copolymers of a C.sub.20 -C.sub.28 .alpha.-olefins and maleic anhydride.
Hazan et al. U.S. Pat. No. 3,560,456 discloses a process for making a copolymer of maleic anhydride and an aliphatic olefin having from 16-18 carbon atoms in the presence of a free radical catalyst and a solvent. The copolymer is precipitated from solution using n-propanol or isopropanol.
de Vries U.S. Pat. No. 3,231,458 discloses a high molecular weight copolymer of olefins of from about 2 to about 20 carbon atoms and diolefins of from about 5 to about 20 carbon atoms reacted with maleic anhydride to form a succinic anhydride-substituted adduct said to have rust inhibiting, dispersing and thickening characteristics in liquid hydrocarbon compositions, such as fuels and lubricants.
Nalesik, et al. U.S. Pat. No. 4,919,683 discloses a stabilizer for a middle distillate fuel-oil which is an aromatic polyamine succinimide derivative of an ethylene/C.sub.3 -C.sub.18 .alpha.-olefin copolymer grafted with maleic anhydride.
Gutierrez et al. U.S. Pat. No. 4,866,135 discloses a reaction product of a C.sub.5 -C.sub.9 lactone adduct of a maleic anhydride grafted ethylene/C.sub.3 -C.sub.28 .alpha.-olefin polymer with an N-containing heterocyclic aminoalkyl derivative. The polymeric lactone derivatives are said to be useful as dispersant additive for fuel and lubricating oils.
Bridger U.S. Pat. No. 4,548,725 discloses a lubricant additive said to reduce low temperature microcrystalline wax formation in hydro-dewaxed stock made by reacting an alcohol with a maleic anhydride-olefin copolymer.
Mehmedbasich et al. U.S. Pat. No. 3,531,440 discloses succinate ester modified polymers of C.sub.6 -C.sub.18 .alpha.-olefins employed as dispersants in fuels.